Internal combustion engines generate heat during operation that is released into the environment through exhaust gas emissions. Modern emission controls systems may utilize energy, in the form of heat from the exhaust gas, to operate various components, for example, Diesel Particulate Filters (DPF). In other cases, heat may be undesirable and removed by use of other components and systems.
One example of a case where additional heat is desirable for the operation of an engine is the operation of a DPF, which depends on a reaction that occurs internally to the DPF and burns particulates that have accumulated therein. Some engines incorporate thermal shielding on their exhaust systems to contain exhaust heat and make it available for emissions components. Heat makes the regeneration of the DPF more efficient. One example of a case where removal of heat is required for proper operation of the engine is in an exhaust gas recirculation (EGR) system, which recirculates cooled exhaust gas into an intake of the engine. EGR systems typically use exhaust gas coolers to remove heat from an exhaust gas stream during recirculation.
Even though heat input may be desirable for some engine systems, heat removed from other systems that is typically rejected back to the engine is undesirable. Heat rejected and/or generated internally to the engine is removed from the engine by a cooling system. Typical cooling systems promote efficient operation of the engine and protect heat sensitive systems. Thermally conductive fluids, that include for instance oil or engine coolant, carry heat collected from within the engine and/or engine components to a radiator, which then expels the heat to the environment.
Accordingly, there is a need for heat management in an engine that reduces undesirable internal heat load to the engine.